Gaseous medium for a hot-gas reciprocating apparatus



March 24, 1964 R. J. MEIJER 3,126,348

GASEOUS MEDIUM FOR A HOT-GAS RECIPROCATING APPARATUS Filed Feb. 2, 1959 INVENTOR ROELF JAN MEI'JER AGENT United States Patent 3,126,348 GASEOU MEDTUM FUR A HGT-GAS RECERGCATTNG APPARATUS lRoeli Jan Meiier, Emmasingel, Eindhoven, Netherlands,

assignor to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Fiied Feb. 2, 1959, Ser. No. 790,434 Ciairns priority, appiication Netheriands Feb. 15, 1958 2 Claims. (Cl. 252-67) Hot-gas reciprocating engines having a closed cycle are known which contain a working medium consisting in part of hydrogen. The term hot-gas reciprocating engine having a closed cycle is to be understood to mean an engine in which a medium is invariably in the gaseous state and is alternatively compressed and expanded at different temperatures. It the expansion takes place at a temperature higher than that during compression, the hot-gas reciprocating engine constitutes a hot-gas reciprocating motor. If, however, the expansion takes place at a temperature lower than that during compression, the hot-gas reciprocating engine constitutes either a refrigerator operating on the reversed principle of a hot-gas reciprocating engine or a heat pump, dependent upon the temperature level of the expansion.

Starting from the working medium known for hot-gas reciprocating engines, the medium consists in part of hydrogen, the hot-gas reciprocating engine according to the present invention is characterized in that the working medium consists of a gas mixture free of oxygen, in which the percentage by weight of hydrogen is at least three and at most twenty.

The use of a mixture free of oxygen affords the advantage that the possibility of the inner parts of the hot-gas reciprocating engine being oxidized is non-existent. This advantage is important, more particularly if the hot-gas reciprocating engine is a hot-gas reciprocating motor, in connection with the very high temperatures then occurring. A further advantage is obtained by choosing hydrogen as one of the components in the gas mixture constituting the working medium of the engine, since traces of lubricating oil which might be present in the space in which the thermodynamic cycle is accomplished and which could lead to contamination of the interior of the engine are hydrated by hydrogen and converted into nonharmful gaseous hydrocarbons. The lubricating oil thus cannot result in contamination of the engine. In this connection it has been found that a percentage by weight of 3% of hydrogen in the gas mixture is already sufficient. The risk of inflammation if the gas filling should leak to the exterior is extremely small if the maximum percentage by weight of hydrogen in the gas mixture is chosen to be 20 and preferably 10.

If in a further embodiment of the hot-gas reciprocating engine according to the invention, helium is chosen for the greater part of the remaining portion of the gas mixture which serves as the working medium, then a working medium is obtained which leads to extremely low losses also in connection with its resistance to flow in the engine.

In order that the invention may be readily carried into efiect, one embodiment will now be described in detail by way of example, with reference to the accompanying drawing showing a hot-gas reciprocating engine of the displacer type.

A displacer 2 and a piston 3 are adapted to move in a cylinder 1, the displacer 2 being coupled by means of a displacer rod 4 and a driving rod 5 to a crank 6 on a crank shaft, 7 of the engine. The piston 3 is connected ice by means of two piston rods 8 and 9 to two cranks 10 and 11, which also form parts of the crank shaft 7. The cranks 10 and 11, on the one hand, and the crank 6, on the other hand, enclose a certain angle determined by the prescribed movement of the displacer 2 with respect to the piston 3.

The hot space 12, which is situated over the displacer 2 in the cylinder 1, communicates freely through a heater 1.3, a regenerator 14 and a cooler 15 with the cold space 16, situated between the displacer 2 and the piston 3. Both the hot space 12 and the cold space 16 vary periodically between a minimum volume, which is usually chosen as small as possible, and a maximum volume. The working space of the engine, which is constituted by the hot space 12, the volume of the heater 13, of the regenerator 14 and of the cooler 15 intended for the working medium, and the cold space 16 contains the working medium which in this example consists of a gas mixture free of oxygen, which contains 5% by weight of hydrogen and otherwise helium. The heater is externally heated by a source of heat, indicated by arrows 17. The heat absorbed by the cooler 15 is dissipated by means of a cooling liquid, for example water, and for this purpose, the cooler is provided with a liquid supply channel 18 and a liquid discharge channel 19.

Since the movement of the displacer 2 and of the piston 3 are relatively chosen so that in this engine the expansion of the working medium takes place at a temperature higher than that during compression, this engine operates as a motor, converting the heat provided by the burners 17 into mechanical energy which may be taken from the crank shaft 7.

The process of compression and expansion during one revolution of crankshaft 7 may be described by the following four phases.

Phase 1.The working medium is contained mainly in the cooled compression space 16 where it is compressed by a main piston 3 to the maximum pressure.

Phase 2.The displacer 2 moves the compressed gas from the compression space 16 to the hot expansion space 12 through cooler 15, regenerator 14, and heater 13. The heat of compression is carried off by the liquid cooler 15. The gas is heated by the passage through regenerator 14.

Phase 3.The gas is expanded in hot space 12 and the heat produced is transferred to heater 13. This is accomplished by the simultaneous downward movement of the piston 3 and the displacer 2.

Phase 4.The hot gas is driven back to the compression space 16 by the return motion of the displacer 2 in an upward direction. The working medium gives off heat to the regenerator which was absorbed during the second phase.

What is claimed is:

l. A gaseous medium for a hot-gas reciprocating apparatus consisting of from 3% to 20% by weight of hydrogen, the remainder and major part of said medium consisting essentially of helium, and said medium being substantially oxygen-free.

2. A gaseous medium for a hot-gas reciprocating apparatus consisting essentially of 10% by Weight of hydrogen, and said medium being substantially oxygen-free, the remainder and major part of said gaseous medium consisting essentially of helium.

References Cited in the file of this patent UNITED STATES PATENTS 2,453,886 Ackeret Nov. 16, 1948 2,602,871 Noland et al. July 8, 1952 2,764,879 De Lange Oct. 2, 1956 

1. A GASEOUS MEDIUM FOR A HOT-GAS RECIPROCATING APPARATUS CONSISTING OF FROM 3% TO 20% BY WEIGHT OF HYDROGEN, THE REMAINDER AND MAJOR PART OF SAID MEDIUM CONSISTING ESSENTIALLY OF HELIUM, AND SAID MEDIUM BEING SUBSTANTIALLY OXYGEN-FREE. 